1. Field of the Invention
The present invention relates to a process for the preparation of an oxazoline compound which is easily chemically converted to .gamma.-amino-.alpha.-hydroxy acid (hereinafter, called ".beta.-a-.alpha.-h") or .gamma.-amino-.beta.-hydroxy acid (hereinafter, called ".gamma.-a-.beta.-h") exhibiting a strong pharmacological activity.
2. Description of the Prior Art
.beta.-a-.alpha.-h and .gamma.-a-.beta.-h are of great interest as very useful compounds because of having a variety of pharmacological activity. Examples of these compounds include (2R, 3S)-N-benzoyl-3-phenylisoserine of the following formula I which is a side chain of Taxol useful as an anti-cancer agent, (2S,3S)-3-amino-2-hydroxy-4-phenylbutanoic acid of the following formula II which is a non-leucine moiety of bestatine exhibiting immuno-modulating, anti-cancer and anti-fungal actions, and statin of the following formula III which is ACE (an Angiotensin Converting Enzyme) inhibitor, and 4-amino-3-hydroxy-5-phenylpentanoic acid which is an analogue of statin represented by the following formula IV. ##STR1##
There were disclosed many processes for the preparation of .beta.-a-.alpha.-h and .gamma.-a-.beta.-h. The preparation of (2R,3S)-N-benzoyl-3-phenylisoserine, which is a side chain of Taxol, was described in Tetrahedron Letters., 1994, 35, 2845-2848, 1994, 35, 9289-9292, J. Org. Chem., 1994, 59, 1238-1240, and J. Am. Chem. Soc., 1995, 117, 7824-7825. Moreover, David et al., in Tetrahedron Letters, 1994, 26, 4483-4484, has reported the preparation of an oxazoline compound which was easily chemically converted to (2R,3S)-N-benzoyl-3-phenylisoserine.
Furthermore, the preparation of (2S,3S)-3-amino-2-hydroxy-4-phenylbutanoic acid, which is a non-leucine moiety of bestatine, was disclosed in Tetrahedron Letters, 1995, 36, 909-912; Tetrahedron Letters, 1994, 35, 6123-6126; and Tetrahedron Letters, 1993, 34, 7557-7560.
Additionally, the preparations of statine represented by the above formula III, and of 4-amino-3-hydroxy-5-phenylpentanoic acid represented by the above formula IV, were described in J. Org. Chem., 1997, 62, 2292-2297; J. Org. Chem., 1995, 60, 6248-6249; U.S. Pat. No. 4,803,292; and Tetrahedron Letters, 190, 31, 7359-7362.